Wireless Power Can Drive Tiny Electronic Devices in the GI Tract

Imagers, gastric pacemakers and other diagnostic and therapeutic tools could someday transform the way diseases of the gastrointestinal tract are measured and treated. But in order for these electronic devices to work, they need a power source. Traditional power sources, such as batteries, can be incompatible with the mucosal lining of the gastrointestinal tract and have a limited lifespan within the body. A more promising possibility is to power electronic devices from outside the body or potentially by the body.

In two studies published in Nature Biomedical Engineering and another study published in Scientific Reports, investigators from Brigham and Women’s Hospital (BWH), Massachusetts Institute of Technology and The Charles Stark Draper Laboratory report that ingestible electronic capsules, complete with on board sensing and communication modules capable of sending and receiving radio signals wirelessly, can safely be powered by harnessing the use of gastric acid as well as the movement in the gastrointestinal tract. Additionally, wireless transmission was also capable of powering ingestible electronic systems. The new work makes wireless medical electronics for treating the gastrointestinal tract one step closer to reality.

“Electronic devices that can be placed in the gastrointestinal tract for prolonged periods of time have the potential to transform how we evaluate and treat patients. This work describes the first example of remote, wireless transfer of power to a system in the stomach in a large preclinical animal model – a critical step toward bringing these devices into the clinic,” said co-corresponding author Carlo “Gio” Traverso, MD, PhD, a gastroenterologist and biomedical engineer at BWH.

Other medical devices – such as cochlear implants or neural probes – use a well-established technique known as near-field coupling to deliver power wirelessly. But ingestible devices must be small enough to be swallowed and, moreover, lie a significant distance from the surface of the body, making this technique unattainable for most gastrointestinal electronics. A glavanic cell and piezoelectric systems to a new technique known as mid-field coupling provide alternative ways to deliver power to deeply implanted devices or harvest energy from the environment. Mid-field coupling operates at higher frequencies to deliver power two to three times more efficiently.

“We are very excited about this work which we feel can someday offer many new opportunities for oral drug delivery of different molecules,” said co-corresponding author Robert Langer, Institute Professor from the Harvard-MIT Division of Health Sciences and Technology.

“In further work, we would like to expand on these measurements by characterizing the effects of animal size, antenna depth, orientation and more on transmission and energy harvesting efficiency to make transmission and harvesting more efficient,” said Dr. Traverso.